• Korean Journal of Applied Biomechanics
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• v.33 no.4
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• pp.155-163
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• 2023

Objective: The purpose of this study is to identify the difference in the quality of muscle contraction and kick movements according to the presence or absence of back pain in body kick movements of mixed martial arts athletes. Method: In this study, four athletes (32.75 ± 4.79 yrs, 172.50 ± 5.20 cm, 77.73 ± 13.28 kg) who have suffered chronic back pain for more than three months and scored 12 points in the Korean version of ODI. Four painless athletes (33.50 ± 4.04 yrs, 174.25 ± 3.10 cm, 83.50 ± 10.21 kg) participated. Results: During the body kick operation, the pain group had significantly higher muscle activity in the right Transversus abdominis and right Rectus femoris compared to the normal group (p<.05). In the rectus abdominis, the muscle activity was significantly lower than that of the normal group (p<.05). Also, the pain group has a higher toe speed than the normal group Significantly slow (p<.05), there was a delay in contraction of the Transversus abdominis. Conclusion: The results of this study suggest that chronic pain in the lumbar spine degrades the core's function, resulting in inefficient coordination such as Transversus abdominis contraction delay and Transversus abdominis and Rectus femoris excessive activation to compensate for it.

• Korean Journal of Applied Biomechanics
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• v.24 no.4
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• pp.367-373
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• 2014

Most athletes execute rhythmic hop as a preparatory motion in Taekwondo sparring. The purpose of this study was to investigate the effect of rhythmic hop on the response times and kicking velocities of Taekwondo kicks. Twelve male elite Taekwondo athletes performed a roundhouse kick and a back kick as fast as possible immediately after seeing an external stimulus in rhythmic hop and in no hop, respectively. The three-dimensional marker data of the whole body were measured at sampling rate of 200 Hz. Paired t-tests were used to compare dependent measures between hop and no hop conditions. Results indicated that the rhythmic hop did not affect response time statistically but improved the kicking velocity significantly than no hop did. Different instants of detecting an external stimulus in rhythmic hop for the back kick showed significantly different response times. Conclusively, rhythmic hop is recommendable for the purpose of kicking velocity, but not for the purpose of response time. Athletes should be careful in executing rhythmic hop as their preparatory motions for the back kick, since the response time could be shortened or lengthened according to the instant of detecting an external stimulus.

• Korean Journal of Applied Biomechanics
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• v.15 no.1
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• pp.29-44
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• 2005

The purpose of this study is to reveal the effects of two different kicks, the drop kick and the punt kick, into the kicking motion, through the kinetic comparative analysis of the kicking motion, which is conducted when one kicks a soccer goal. To grasp kinetic changing factors, which is performed by individual's each body segment, I connected kicking motions, which were analyzed by a two dimension co-ordination, into the personal computer to concrete the digits of it and smoothed by 10Hz. Using the smoothed data, I found a needed kinematical data by inputting an analytical program into the computer. The result of comparative analysis of two kicking motions can be summarized as below. 1. There was not a big difference between the time of the loading phase and the time of the swing phase, which can affect the exact impact and the angle of balls aviation direction. 2. The two kicks were not affected the timing and the velocity of the kicking leg's segment. 3. In the goal kick motion, the maximum velocity timing of the kicking leg's lower segment showed the following orders: the thigh(-0.06sec), the lower leg(-0.05sec), the foot(-0.018sec) in the drop kick, and the thigh(-0.06sec), the lower leg(-0.05sec), the foot(-0.015sec) in the punt kick. It showed that whipping motion increases the velocity of the foot at the time of impact. 4. At the time of impact, there was not a significant difference in the supporting leg's knee and ankle. When one does the punt kick, the subject spreads out his hip joint more at the time of impact. 5. When the impact performed, kicking leg's every segment was similar. Because the height of the ball is higher in the punt kick than in the drop kick, the subject has to stretch the knees more when he kicks a ball, so there is a significant affect on the angle and the distance of the ball's flying. 6. When one performs the drop kick, the stride is 0.02m shorter than the punt kick, and the ratio of height of the drop kick is 0.05 smaller than the punt kick. This difference greatly affects the center of the ball, the supporting leg's location, and the location of the center of gravity with the center of the ball at the time of impact. 7. Right before the moment of the impact, the center of gravity was located from the center of the ball, the height of the drop kick was 0.67m ratio of height was 0.37, and the height of the punt kick was 0.65m ratio of height was 0.36. The drop kick was located more to the back 0.21m ratio of height was 0.12, the punt kick was located more to the back 0.28m ratio of height was 0.16. 8. There was not a significant difference in the absolute angle of incidence and the maximum distance, but the absolute velocity of incidence showed a significant difference. This difference is caused from that whether players have the time to perform of not; the drop kick is used when the players have time to perform, and punt kick is used when the players launch a shifting attack. 9. The surface reaction force of the supporting leg had some relation with the approaching angle. Vertical reaction force (Fz) showed some differences in the two movements(p<0.05). The maximum force of the right and left surface reaction force (Fx) didn't have much differences (p<0.05), but it showed the tendency that the maximum force occurs before the peak force of the front and back surface (Fy) occurs.

• Journal of Chest Surgery
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• v.48 no.4
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• pp.281-284
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• 2015

We present the case of a 38-year-old woman admitted to our outpatient clinic with accelerating back pain and fatigue following a kick to her back by her husband. Upon arrival, we detected ST segment elevation in the D1, aVL, and V2 leads and accelerated idioventricular rhythm. She had pallor and hypotension consistent with cardiogenic shock. We immediately performed coronary angiography and found a long dissection starting from the mid-left main coronary artery and progressing into the mid-left anterior descending (LAD) and circumflex arteries. She was then transferred to the operating room for surgery. A saphenous vein was grafted to the distal LAD. Since the patient was hypotensive under noradrenaline and dopamine infusions, she was transferred to the cardiovascular surgery intensive care unit on an extracorporeal membrane oxygenator and intra-aortic balloon pump. During follow-up, her blood pressure remained low, at approximately 60/40 mmHg, despite aggressive inotropic and mechanical support. On the second postoperative day, asystole and cardiovascular arrest quickly developed, and despite aggressive cardiopulmonary resuscitation, she died.

• Journal of the Korean Applied Science and Technology
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• v.37 no.4
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• pp.870-877
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• 2020

The purpose of this study is to compare and analyze the effects of stepping-in-place tempo and roundhouse kick types on response time. Fifteen males participated in this experiment. All have over ten years of experience and hold a forth dan(degree) black belt in taekwondo. The task is when the participants are doing stepping in place they respond to the light stimulus as fast as they can do roundhouse kick. Five different stepping in place tempos (100, 120, 140, 160, and 180 bpm) and four different types of roundhouse kick(front leg body roundhouse kick, front leg head roundhouse kick, back leg body roundhouse kick, and back leg head roundhouse kick) were used. Three measurements were taken for each of the different combinations of conditions for a total of 60 measurements. For data analysis, two-way ANOVA with repeated measures was used and pair-wise comparisons were performed using bonferroni statistics. The results show that there was significant difference interaction effect between stepping in place tempo and roundhouse kick type in the response time. And, there were significant difference in main effect of response time in accordance with stepping in place tempo and roundhouse kick type. The response time of roundhouse kick was the fastest at 160 bpm of stepping in place tempo, but there was no significant difference between 140 and 160 bpm. Front leg body roundhouse kick was the fastest. And, the response time was the fastest when front leg body roundhouse kicked at 140 bpm of stepping in place tempo. Stepping in place tempo between 140 and 160 bpm is the most effective to optimize the response time. And, More effective response time was front leg roundhouse kick as compared with back leg roundhouse kick and, body roundhouse kick as compared with head roundhouse kick. The findings in this study will provide useful information for performance improvement and will help with strategy for taekwondo competition.

• Korean Journal of Applied Biomechanics
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• v.18 no.1
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• pp.117-127
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• 2008

The purpose of this study was to investigate the relationship between research of mechanical friction and Taekwondo kick performance. For this a Taekwondo kick performance test, A.F.T.S.(Automated Footwear Testing System) and survey about fitting was used. There was a statistically significant difference between all the Taekwondo shoe types. While performing the roundhouse kick there were statistically significant differences in the peak free moment(p=.01) and peak plantar pressure between type A and B. Comfort testing revealed that there were statistically significant difference between type A and B in the five comfort variables tested but not between type B and Type C. There was statistically significant differences between each of the Taekwondo shoes but there was no relationship between the performance and the results of the survey.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.1
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• pp.83-90
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• 2008

Taekwondo is a martial art form and sport that uses the hands and foot for attack and defense. Taekwondo basic motion is composed of the breaking, competition and poomsea motion. In the side kick among the competition motion, the impact force is larger than other kinds of kicks. The side kick with the front foot can be made in two steps. In the first step, the front foot is stretched forward from back stance free-fighting position. For the second step, the rear foot is followed simultaneously. Then, the kick is executed while entire body weight rests on the rear foot. In this paper, impact analysis of the human model for hitting posture is carried out. The ADAMS/LifeMOD is used in hitting modeling and simulation. The simulation model creates the human model to hit the opponent. As the results, the dynamic analysis of human muscle were presented.

• Korean Journal of Applied Biomechanics
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• v.21 no.1
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• pp.57-65
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• 2011

This research was conducted to biomechanically analyze Tippelt motion in parallel bars, and establish technical understanding. To achieve that goal, the performances of the Tippelt acts carried out by five world top-class national gymnasts in the parallel bars 3-dimensional cinematographic analysis and EMG analysis were conducted and following conclusion were obtained. The Tippelt motions of excellent national gymnasts perform tap motion through the down swing of a large circular movements, and perform kick-out motion rapidly extending shoulder joint angle and hip joint angle with the trunk in a position close to perpendicular position at the vertical downwardness of the grasping the bars. At this time, if handstand starting the movement is too delayed or rapidly down swung, it was shown that from the initial falling, unnecessary muscular power was wasted in trapezius, anterior deltoid, erector spinae, latissimus dorsi, upper rectus abdominis, lower rectus abdominis. The muscular parts in tap motion generating muscle action potential were pectoralis major, rectus femoris, upper rectus abdominis, lower rectus abdominis, and those in kick-out motion were upper rectus abdominis, lower rectus abdominis, trapezius and anterior deltoid.

• Journal of KIISE:Software and Applications
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• v.27 no.7
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• pp.712-722
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• 2000

In this paper, we suggest and test a classification technique of offence pattern from group formation to automatically index highlights of soccer games. A BP (Back-propagation) neural nets technique was applied to the information of the position of both the player and the ball on a ground, and the distance between the player and the ball to identify the group formation in space and time. The real soccer game scenes including '98 France World Cup were used to extract 297 video clips of various types of offence patterns; Left Running 60, Right Running 74, Center Running 72, Corner-kick 39 and Free-kick 52. The results are as follows: Left Running comes to 91.7%, Right Running 100%. Center Running 87.5%, Corner-kick 97.4% and Free-kick 75%, and these showed quite a satisfactory rate of recognition.

• Korean Journal of Applied Biomechanics
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• v.16 no.3
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• pp.43-51
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• 2006

The purpose of this study was to analyze kinematic variables during turing back kick motion of Taekwondo. The subjects of this study were the 4 skilled and 4 unskilled of male university player in respectively. The experiment of this study was used two 16mm high speed cameras and its speed 125 frames/s. Analysis of this data was three dimensional cinematography using KWON3D program package. The results were as following; 1. In the elapsed time, there was no significance difference statically between a skilled and unskilled group. But skilled group was more fast during the motion of I phase. And unskilled group was more fast during the motion of II phase so called force production section, which had an influence on Diechagi's velocity. 2. In the center of gravity of human body, the changing of it was $1.10{\pm}0.04m$, $1.12{\pm}0.03m$ of LFM(left foot movement) and $1.36{\pm}0.08m$, $1.39{\pm}0.09m$ of RKF(right knee flection), and $1.44{\pm}0.08m$, $1.42{\pm}0.09m$ of RFI(right foot impact). There was no significance difference statically between the two groups. 3. The velocity of heel on impact was 1.13m/s in the skilled group and 1.23m/s in the unskilled group, when each angle of knee was $110.4{\pm}10.9deg/s$, $114.8{\pm}28.4deg/s$. The maximum velocity of each performance was reached before the RKF, and the velocity and angle at impact along by two groups did not show any significant difference statically. 4. In the angular velocity of just RKF of lower leg, there was significance difference statically between the two groups(p<.05).